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In vitro and in situ evaluation of the efficacy of bleaching gels containing hydrogen peroxide associated with Biosilicate® doped with Manganese Oxide and activated with violet light

Grant number: 23/03511-8
Support Opportunities:Scholarships in Brazil - Master
Effective date (Start): December 01, 2023
Effective date (End): February 28, 2025
Field of knowledge:Health Sciences - Dentistry
Principal Investigator:Vanessa Cavalli Gobbo
Grantee:Rafael Dascanio
Host Institution: Faculdade de Odontologia de Piracicaba (FOP). Universidade Estadual de Campinas (UNICAMP). Piracicaba , SP, Brazil


Despite the bleaching efficacy of vital teeth with 35% H2O2, studies point to a decrease in mineral content, changes in enamel surface morphology, and cytotoxicity of odontoblastic cells. To reverse such effects, the objective of this research was to develop and analyze low-bleaching gel concentration, containing Bioglass 45S5® (BG) doped with manganese oxide (MnO2) and associated with violet light (LED). In phase 1, the BG will be doped with manganese oxide (MnO_BG) through the traditional route of oxide fusion. Photocatalytic analysis of the compound will be performed in a light absorption spectrophotometer. In step 2, pigmented enamel blocks will be treated with 35% H2O2 (positive control), 6% H2O2 associated with an experimental gel containing BG or MnO_BG (0 and 10 wt%) and associated or not with a violet LED light (405 - 410 nm). The negative control will be untreated enamel blocks immersed in artificial saliva during the experiment. Whitening will be carried out in 3 sessions of 30 min each, at intervals of 7 days. The blocks will be evaluated for (n=10): color change (”E), whitening index (”WID), color parameters (L*, a*, b*) in a digital spectrophotometer, mineral content [surface microhardness (KHN ) and evaluation of bands (CO2-3) and phosphate (PO4-2) in Fourier transform infrared spectroscopy (FTIR)], before and after treatments, and analysis of surface morphology [scanning electron microscopy (SEM) ] at the end of bleaching. In step 3, the blocks will be evaluated for cytotoxicity in cells of the odontoblastic lineage (MTT test, oxidative stress analysis, quantification of PH in extracts, free radical production, cell morphology, and live/dead fluorescence). In step 4, double-blind in situ analysis of treatments. 12 volunteers will use palatal devices containing sterilized enamel blocks for 14 days. The devices will remain in the oral environment and be removed for the in-office bleaching treatment. Whitening will be performed in three 30-minute sessions on the 1st, 7th, and 14th days of treatment. Color evaluations (”E, ”WID, L*, a*, b*) will be performed 24h after each session. Mineral content (KHN) will be determined before and after treatments and morphology (SEM) will be observed after treatments. Data will be submitted for statistical analysis, and according to normality, appropriate tests will be performed (± = 5%).

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